Geochemistry, mineral chemistry and tectonic settings of the older granitoids from East of El-Tor, SW-Sinai, Egypt
The older granitoids of Wadi Hibran-Wadi Mear, East of El-Tor constitute the westernmost outcrops of the granitic intrusion of Sinai massif of Egypt. They intrude small masses of gneisses and are, in turn, invaded by huge masses of younger granites and crosscut by mafic and felsic dyke swarms. They...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1999
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| Sorozat: | Acta mineralogica-petrographica
40 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24880 |
| Tartalmi kivonat: | The older granitoids of Wadi Hibran-Wadi Mear, East of El-Tor constitute the westernmost outcrops of the granitic intrusion of Sinai massif of Egypt. They intrude small masses of gneisses and are, in turn, invaded by huge masses of younger granites and crosscut by mafic and felsic dyke swarms. They consist of trondjemite-granodiorite (TR-GD) suite and belong to the low- to medium K calc-alkaline series. The TR suite comprises quartz-diorite, quartz monzodiorite and tonalite, meanwhile the GD suite includes proper granodiorite. Amphiboles are calcic-type and vary in composition from magnesio-hornblende in TR to ferroedenitic hornblende in GD. Amphiboles from more evolved rock-types contain higher values of mg [Mg/(Mg+Fe) ratio] than those of the coexisting biotites. Biotite mg-values decrease with increase Si from TR to GD rocks. Chemical parameters of amphiboles, biotites and plagioclases indicate a pressure less than 5 Kb. and temperature of about 700-850 °C for the host TR-GD suite. Based on REE geochemistry, the older granitoids show two different types of REE patterns; A) less differentiated type represented by TR suite and B) differentiated type related to GD suite. The less differentiated type has REE distribution patterns marked by positive Eu anomaly, whereas the differentiated type has wide range of total REE abundance and displays negative Eu anomaly. Both of them have smooth concave REE distribution patterns. These patterns are fairly similar to the models involving partial melting of eclogite/quartz eclogite parents. Tectomagmatic setting reveals that the present granitoids belong to two calc-alkaline mafic magmas emplaced through a pre-plate collision to post-collision regime. They are highly comparable with the volcanic arc granites of active continental margin. |
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| Terjedelem/Fizikai jellemzők: | 77-96 |
| ISSN: | 0365-8066 |